Metal working tool



April 1957 c. ROSENHAGEN 2,787,098

METAL WORKING TOOL Original Filed Oct. 25, 1949 :mwpm

GHorneq United States Patent METAL WORKING TOOL Carl Rosenhagen, Dayton, Ohio 6 Claims. (Cl. 51--184.3)

This invention relates to metal working tools, and more particularly to lapping tools as used in the fine grinding of aperture walls, and more particularly to a two-part telescopically adjustable lapping tool.

This application is a continuation of my pending application Serial No. 123,334, filed October 25, 1949, now abandoned.

While expansible laps have heretofore been known, such prior devices have in the majority of instances embodied an expansible insert or other means for expanding a relatively flexible lapping surface from the interior thereof. The relatively flexible material from which such laps are made is of necessity rather thin in cross section, thereby greatly reducing the useful life of such tools. The prior laps also lack rigidity and do not possess diamensional stability due to the flexible nature of .the material from which they are made and the lack of solid support therefor. It is the purpose of the instant invention to overcome these disadvantages while producing a relatively inexpensive lap which not only maintains dimensional stability but provides a substantially rigid and unyielding lapping surface.

Thus the object of the invention is to simplify the con struction as well as the means and mode of operation of lapping tools as disclosed herein, whereby such tools may not only be economically manufactured, but will be more efficient, accurate and satisfactory in use, adaptable to a wide variety of work, having relatively few parts and be unlikely to get out of repair.

It is a further object of the invention toproduce a lap readily adjustable to a desired diameter.

Another object of the invention is to prolong the useful life of a lap by providing for expansion thereof over a wide range thereby compensating for wear.

A further object of the invention is to maintain the correct shape of the lap over its expansion range.

Still another object of the invention is to provide a lap adaptable for use in an installation Where either one or both ends are supported.

A still further object of the invention is to produce a two-part telescoping type lap in which provision is made for calculated unevenness of wear to maintain proper shape of the lap over its expansion range.

A still further object is to provide a novel and useful lap which may be simply and inexpensively made, for example, by die casting.

A further and important object of the invention is to provide a lap in which the working surfaces are firmly and rigidly supported, thereby preventing flexing thereof during use. I

A further object of the invention is to ,provide means in the surface of the lap for retaining a supply of lapping compound.

A further object of the invention is to provide a lap possessing the advantageous structural features, the in herent meritorious characteristics and the mode of op eration herein mentioned.

With the above primary and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawing, wherein is found the preferred but obviously not necessarily the only form of embodiment of the invention,

Fig. l is a view of the lap of the invention in side elevation, according to one form of installation and use thereof;

Fig. 2 is a view of one element of the lap in longitudinal section;

Fig. 3 is a front end view of the lap of Fig. 2;

Fig. 4 is a view of the lap of the invention in side elevation, according to another form of installation and use thereof;

Fig. 5 is a view in cross section, taken substantially along the line 5-5 of Fig. 1; and

Fig. 6 is a view in cross section, taken substantially along the line 6-6 of Fig. 1.

Like parts are indicated by similar characters of reference throughout the several views.

Referring to the drawing, a lap in accordance with the illustrative embodiment of the invention is constructed and arranged to be supported at its opposite ends, as in Fig. 1 or to be supported at only one end thereof, as in Fig. 4.

In either event, the lap comprises a pair of axially aligned, hollow, cylindrical elements 10 and 11, which when used in the manner of either Fig. 1 or Fig. 4 are identical. Each comprises a base portion 12 from the periphery of which projects circumferentially spaced arcuate prongs or lands 13. In width the prongs 13 taper from relatively wide bases to narrower tips and there is defined between adjacent prongs oppositely tapered slots 14. These slots 14 are so proportioned relative to the prongs 13 that the maximum width of the slots is substantially equal to the minimum width of the prongs.- This is clearly shown in Fig. 3, wherein the ends of the prongs 13 are of substantially the same width as the openings into the intermediate slots 14. The side walls of the prongs 13 are inclined, being approximately radial; with respect to the axis of the element.

According to the further formation of the prongs, each may have in the outer or tip end thereof a recess 15 in the upper surface and such tip end is slightly tapered in a radial direction.

In use, the pronged ends of the elements are interfitted, as shown in Fig. l, the prongs 13 of one element being received in the slots 14 of the other element, and vice versa. The prongs complement one another to producea continuous cylindrical lapping surface at the joint so established.

By reason of the described construction and arrange-- ment of the parts, it will be apparent that a relative axial motion of the elements 10 and 11 will have the effect of expanding the prongs or of allowing them to return from an expanded condition, according to whether the direction of motion is an approaching or separating one. That is, an axial motion of the elements, which results in pushing the prongs 13 deeper into the slots 14 will enforce a radial expansion of the prongs and such motion will be partaken of equally by the prongs on both elements. Similarly, an axial motion in a separating direction allows the prongs to contract. In this manner the diameter of the lapping surface may within reasonable limits be varied.

In an installation as shown in Fig. l the elements 16 and 11 are gripped and held by respective rotatable heads 16 and 17 capable of relative approaching and separating motions, In'applying the tool to the work, the elements and are first compietely separated and the work placed therebetween. Upon movement of the heads toward each other, the elements -10-l1 approach and enter the work, the pronged ends of the elements engaging one another. Such approaching motion is continued until the desired diameter of lapping surface is achieved. Similarly, the elements 10 and 11 are completely separated for removal of the Work.

In an installation as shown in Fig. 4 only one end of the lap as end 18 is supported. The other end thereof receives a bolt 13 which is passed axially through the lap assembly and into a tapped recess 19 in the support 19. The bolt 18 maintains the two elements of the lap in assembled relation and by its rotation serves to adjust the elements axially.

While usable in the manner described to obtain a lapping surface diameter to suit the size of hole being lapped, the instant invention has equal application as a means for prolonging the useful life of a lap. Thus assuming that at the start of a lapping operation the parts occupy substantially the positions shown in Figs. 1 and 4, it is possible by extending the prongs 13 progressively deeper into the slots 14 to maintain a substantially con stant lapping surface diameter, compensating for Wear.

The recesses in the outer ends of the prongs 13 allow the tips of the prongs to wear down more rapidly when the lap is highly expanded or when the elements lfl and 11 are telescoped about half the length of the prongs. This feature prevents humping of the prongs, i. e., elevation of the prong tip above the surface of the adjacent prong bases lying on either side of the tip. This together with the radial curvature of the prong tips assists in maintaining a true cylindrical surface on the lap throughout its expansion range. The recesses 15 are further useful as reservoirs or pockets to receive and retain a supply of abrasive material, sometimes advantageously used in lapping operations.

in some instances, particularly in laps of larger diamctcrs, it has beenfoun-d desirable to axially extend the recess 15 toward the base portion 12, as shown at 15. inasmuch. as the tendency of the laps to hump decreases toward the base portions 12, such supplemental recess 15 is of progressively decreasing width and depth as it approaches the base portion 12, it being of greatest size immediately adjacent the recess 15. As in the case with recess 15, the supplemental. recess 15' further provides an elongated reservoir of limited capacity for the storage of abrasive material commonly known as lapping compound.

The construction of the lap is such that it need not be machined, but can be die cast of a suitable metal.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated asdesirable, but which obviously is susceptible of modification in its form, proportions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

While :in order .to comply with the statute the inven tion has been described inlanguage more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into clfect.

Having thus described my invention, I claim:

1. A metal working tool including a pair of cylindrical elements each having on one end thereof a plurality of spaced longitudinally tapered flexible prongs, approximately radial inclined sides thereon, a plurality of spaced tapered slots arranged in alternating relation with said prongs, said slots being rcversely tapered relative to said prongs, the maximum width of said slots being substantially equal to the minimum width of said prongs, the construction and arrangement being such that the tips of thc prongs of one element interfit with the tips of the prongs of the other element to define a continuous cylindrical metal working surface, said inclined prong sides cooperating with one another to make said cylindrical surface variable in diameter in response to relative axial adjustment of said elements and the flexible intcrfitting prongs carried thereby.

2. A metal Working tool including a pair of cylindrical elements, a plurality of circumferentially spaced tapered prongs integrally formed on one end of said elements, each of said prongs being formed with an arcuate outer surface and inclined side walls. a plurality of spaced tapered slots arranged intermediate said spaced prongs,

said slots being 'revers'ely tapered with the maximum width of said slots'substantially equal to the minimum width of said prongs, whereby the prongs of one element will intcriit With the prongs of the other element to define a continuous cylindrical metal working surface, said elements being axially adjustable with respect to each other to vary the diameter of said continuous metal working surface formed by said abutting interfitted prongs.

3. A metal working tool including a pair of like axially aligned cylindrical elements, alternate spaced longitudinally tapered elongated prongs and slots integrally formed in one end of said elements, the ends of said elements interfitting with the prongs of one element received in the slots of the other element and vice versa, to thereby form a continuous cylindrical metal working surface, a longitudinally inclined surface in the working surface of each prong adjacent the outer ends thereof, inclined side edges on each prong complementary to the side edges on adjacent prongs, which together with the longitudinally tapered'formation of the prongs provide a construction and arrangement of parts such that cylindrical cutting diameter of the tool is varied upon axial motion of the elements, one relative to the other, and means for drawing the two elements and their prongs and slots axially into and out of one another.

4. A metal working tool including a pair of cylindrical coaxial elements, a plurality of tapered prongs axially extending from each of .said elements into interfitting engagement, the prongs ofene of said elements being located intermediate the prongs on the other opposed element, a radially tapered surface on each prong adjacent the end thereof, a recess centrally disposed within the periphery of said prongs adjacent the ends thereof and in spaced relation with the sides of said prongs, and a continuing elongated groove-of gradually decreasing width and depth extending rearwardly from the recess toward the cylindrical element, said groove being centrally disposed relative to the prongs.

5. A metal working tool assembly including a pair of opposed axially aligned inter-fitting cylindrical elements capable of relative axial movement toward and from one another, cooperating surfaces on the interfitting portions thereof causing .a radial expansion of the interfitting portions upon movement of the elements one toward the other, and a centrally disposed recess upon the periphery of the "interfitting portions extending longitudinally thereof from one end of the elements toward the other of progressively decreasing width and depth.

6. A metal working tool including a pair of axially aligned cylindrical elements respectively having cooperating longitudinal and reversely tapered elongated prongs and slots integrally formed in one end thereof, said ends of said elements interfitting with the prongs of one element received in the slots of the other and vice versa to thereby form a continuous cylindrical metal working surface, said prongs and said slots being of substantially com- 10 plementary width over a greater portion of their length,

the width of the slots being narrower at their inner end than the width of the corresponding part of the interfitting prongs, an inclined edge formation on said tapered prongs, and means for adjusting said cylindrical elements in relation to each other to effect radial adjustment of said prongs.

References Cited in the file of this patent UNITED STATES PATENTS 

